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Chang T, Hunt BPV, Hirai J, Suttle CA. Divergent RNA viruses infecting sea lice, major ectoparasites of fish. PLoS Pathog 2023; 19:e1011386. [PMID: 37347729 DOI: 10.1371/journal.ppat.1011386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 04/25/2023] [Indexed: 06/24/2023] Open
Abstract
Sea lice, the major ectoparasites of fish, have significant economic impacts on wild and farmed finfish, and have been implicated in the decline of wild salmon populations. As blood-feeding arthropods, sea lice may also be reservoirs for viruses infecting fish. However, except for two groups of negative-strand RNA viruses within the order Mononegavirales, nothing is known about viruses of sea lice. Here, we used transcriptomic data from three key species of sea lice (Lepeophtheirus salmonis, Caligus clemensi, and Caligus rogercresseyi) to identify 32 previously unknown RNA viruses. The viruses encompassed all the existing phyla of RNA viruses, with many placed in deeply branching lineages that likely represent new families and genera. Importantly, the presence of canonical virus-derived small interfering RNAs (viRNAs) indicates that most of these viruses infect sea lice, even though in some cases their closest classified relatives are only known to infect plants or fungi. We also identified both viRNAs and PIWI-interacting RNAs (piRNAs) from sequences of a bunya-like and two qin-like viruses in C. rogercresseyi. Our analyses showed that most of the viruses found in C. rogercresseyi occurred in multiple life stages, spanning from planktonic to parasitic stages. Phylogenetic analysis revealed that many of the viruses infecting sea lice were closely related to those that infect a wide array of eukaryotes with which arthropods associate, including fungi and parasitic tapeworms, implying that over evolutionary time there has been cross-phylum and cross-kingdom switching of viruses between arthropods and other eukaryotes. Overall, this study greatly expands our view of virus diversity in crustaceans, identifies viruses that infect and replicate in sea lice, and provides evidence that over evolutionary time, viruses have switched between arthropods and eukaryotic hosts in other phyla and kingdoms.
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Affiliation(s)
- Tianyi Chang
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, Canada
| | - Brian P V Hunt
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, Canada
- Institute for the Oceans and Fisheries, University of British Columbia, Vancouver, Canada
- Hakai Institute, Campbell River, Canada
| | - Junya Hirai
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan
| | - Curtis A Suttle
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, Canada
- Institute for the Oceans and Fisheries, University of British Columbia, Vancouver, Canada
- Hakai Institute, Campbell River, Canada
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
- Department of Botany, University of British Columbia, Vancouver, Canada
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Piasecki W, Venmathi Maran BA, Ohtsuka S. Are We Ready to Get Rid of the Terms “Chalimus” and ”Preadult” in the Caligid (Crustacea: Copepoda: Caligidae) Life Cycle Nomenclature? Pathogens 2023; 12:pathogens12030460. [PMID: 36986382 PMCID: PMC10053709 DOI: 10.3390/pathogens12030460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 03/07/2023] [Accepted: 03/08/2023] [Indexed: 03/17/2023] Open
Abstract
In view of recent studies, we suggest that the term “preadult” should not be used in scientific reports on Copepoda parasitic on fishes as having no explicit meaning or further justification. Consequently, the term “chalimus” with its use currently restricted in the Caligidae to at most two instars in the life cycles of species of Lepeophtheirus, also becomes redundant. In our new understanding, both the chalimus and preadult stages should be referred to as the respective copepodid stages (II through V, in integrative terminology). The terminology for the caligid copepod life cycle thereby becomes consistent with that for the homologous stages of other podoplean copepods. We see no justification for keeping “chalimus” and “preadult” even as purely practical terms. To justify this reinterpretation, we comprehensively summarize and reinterpret the patterns of instar succession reported in previous studies on the ontogeny of caligid copepods, with special attention to the frontal filament. Key concepts are illustrated in diagrams. We conclude that, using the new integrative terminology, copepods of the family Caligidae have the following stages in their life cycles: nauplius I, nauplius II (both free-living), copepodid I (infective), copepodid II (chalimus 1), copepodid III (chalimus 2), copepodid IV (chalimus 3/preadult 1), copepodid V (chalimus 4/preadult 2), and adult (parasitic). With this admittedly polemical paper, we hope to spark a discussion about this terminological problem.
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Affiliation(s)
- Wojciech Piasecki
- Institute of Marine and Environmental Sciences, University of Szczecin, ul. Adama Mickiewicza 16, 70-383 Szczecin, Poland
- Correspondence:
| | | | - Susumu Ohtsuka
- Takehara Station, Setouchi Field Science Center, Graduate School of Integrated Sciences for Life, Hiroshima University, Takehara 725-0024, Japan;
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3
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Borchel A, Komisarczuk AZ, Nilsen F. Sex differences in the early life stages of the salmon louse Lepeophtheirus salmonis (Copepoda: Caligidae). PLoS One 2022; 17:e0266022. [PMID: 35358250 PMCID: PMC8970357 DOI: 10.1371/journal.pone.0266022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 03/11/2022] [Indexed: 11/18/2022] Open
Abstract
Salmon lice are ectoparasites on salmonids and feed on blood, mucus, and skin from their hosts. This causes high annual costs for treatment and control for the aquaculture industry. Salmon lice have a life cycle consisting of eight life stages. Sex determination by eye is only possible from the sixth stage onwards. A molecular sex determination has not been carried out so far, even though few individual sex-linked SNPs have been reported. In the present study, we used known sex-specific SNPs as a basis to sequence the complete sex-specific gene variants and used the sequence information to develop a sex determination assay. This assay could be used to determine the developmental speed of the two sexes already in the earliest life stages. Additionally, we sampled salmon lice in the nauplius II stage, determined the sex of each individual, pooled their RNA according to their sex, and used RNA sequencing to search for differences in gene expression and further sex-specific SNPs. We succeeded in developing a sex-determination assay that works on DNA or RNA from even the earliest larval stages of the salmon louse after hatching. At these early developmental stages, male salmon lice develop slightly quicker than females. We detected several previously unknown, sex-specific SNPs in our RNA-data seq, but only very few genes showed a differential expression between the sexes. Potential connections between SNPs, gene expression, and development are discussed.
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Affiliation(s)
- Andreas Borchel
- Department of Biological Sciences, SLRC—Sea Lice Research Centre, University of Bergen, Bergen, Norway
- * E-mail:
| | - Anna Zofia Komisarczuk
- Department of Biological Sciences, SLRC—Sea Lice Research Centre, University of Bergen, Bergen, Norway
| | - Frank Nilsen
- Department of Biological Sciences, SLRC—Sea Lice Research Centre, University of Bergen, Bergen, Norway
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4
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Zhou Z, Eichner C, Nilsen F, Jonassen I, Dondrup M. A novel approach to co-expression network analysis identifies modules and genes relevant for moulting and development in the Atlantic salmon louse (Lepeophtheirus salmonis). BMC Genomics 2021; 22:832. [PMID: 34789144 PMCID: PMC8600823 DOI: 10.1186/s12864-021-08054-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 10/04/2021] [Indexed: 11/25/2022] Open
Abstract
Background The salmon louse (Lepeophtheirus salmonis) is an obligate ectoparasitic copepod living on Atlantic salmon and other salmonids in the marine environment. Salmon lice cause a number of environmental problems and lead to large economical losses in aquaculture every year. In order to develop novel parasite control strategies, a better understanding of the mechanisms of moulting and development of the salmon louse at the transcriptional level is required. Methods Three weighted gene co-expression networks were constructed based on the pairwise correlations of salmon louse gene expression profiles at different life stages. Network-based approaches and gene annotation information were applied to identify genes that might be important for the moulting and development of the salmon louse. RNA interference was performed for validation. Regulatory impact factors were calculated for all the transcription factor genes by examining the changes in co-expression patterns between transcription factor genes and deferentially expressed genes in middle stages and moulting stages. Results Eight gene modules were predicted as important, and 10 genes from six of the eight modules have been found to show observable phenotypes in RNA interference experiments. We knocked down five hub genes from three modules and observed phenotypic consequences in all experiments. In the infection trial, no copepodids with a RAB1A-like gene knocked down were found on fish, while control samples developed to chalimus-1 larvae. Also, a FOXO-like transcription factor obtained highest scores in the regulatory impact factor calculation. Conclusions We propose a gene co-expression network-based approach to identify genes playing an important role in the moulting and development of salmon louse. The RNA interference experiments confirm the effectiveness of our approach and demonstrated the indispensable role of a RAB1A-like gene in the development of the salmon louse. We propose that our approach could be generalized to identify important genes associated with a phenotype of interest in other organisms. Supplementary Information The online version contains supplementary material available at (10.1186/s12864-021-08054-7).
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Affiliation(s)
- Zhaoran Zhou
- Department of Informatics & Sea Lice Research Centre, University of Bergen, Thormøhlensgate 55, Bergen, 5008, Norway
| | - Christiane Eichner
- Department of Biological Sciences & Sea Lice Research Centre, University of Bergen, Thormøhlensgate 55, Bergen, 5008, Norway
| | - Frank Nilsen
- Department of Biological Sciences & Sea Lice Research Centre, University of Bergen, Thormøhlensgate 55, Bergen, 5008, Norway
| | - Inge Jonassen
- Department of Informatics & Sea Lice Research Centre, University of Bergen, Thormøhlensgate 55, Bergen, 5008, Norway
| | - Michael Dondrup
- Department of Informatics & Sea Lice Research Centre, University of Bergen, Thormøhlensgate 55, Bergen, 5008, Norway.
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The FTZ-F1 gene encodes two functionally distinct nuclear receptor isoforms in the ectoparasitic copepod salmon louse (Lepeophtheirus salmonis). PLoS One 2021; 16:e0251575. [PMID: 34014986 PMCID: PMC8136749 DOI: 10.1371/journal.pone.0251575] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 04/29/2021] [Indexed: 01/21/2023] Open
Abstract
The salmon louse, Lepeophtheirus salmonis, is an ectoparasitic crustacean that annually inflicts substantial losses to the aquaculture industry in the northern hemisphere and poses a threat to the wild populations of salmonids. The salmon louse life cycle consists of eight developmental stages each separated by a molt. Fushi Tarazu Factor-1 (FTZ-F1) is an ecdysteroid-regulated gene that encodes a member of the NR5A family of nuclear receptors that is shown to play a crucial regulatory role in molting in insects and nematodes. Characterization of an FTZ-F1 orthologue in the salmon louse gave two isoforms named αFTZ-F1 and βFTZ-F1, which are identical except for the presence of a unique N-terminal domain (A/B domain). A comparison suggest conservation of the FTZ-F1 gene structure among ecdysozoans, with the exception of nematodes, to produce isoforms with unique N-terminal domains through alternative transcription start and splicing. The two isoforms of the salmon louse FTZ-F1 were expressed in different amounts in the same tissues and showed a distinct cyclical expression pattern through the molting cycle with βFTZ-F1 being the highest expressed isoform. While RNA interference knockdown of βFTZ-F1 in nauplius larvae and in pre-adult males lead to molting arrest, knockdown of βFTZ-F1 in pre-adult II female lice caused disruption of oocyte maturation at the vitellogenic stage. No apparent phenotype could be observed in αFTZ-F1 knockdown larvae, or in their development to adults, and no genes were found to be differentially expressed in the nauplii larvae following αFTZ-F1 knockdown. βFTZ-F1 knockdown in nauplii larvae caused both down and upregulation of genes associated with proteolysis and chitin binding and affected a large number of genes which are in normal salmon louse development expressed in a cyclical pattern. This is the first description of FTZ-F1 gene function in copepod crustaceans and provides a foundation to expand the understanding of the molecular mechanisms of molting in the salmon louse and other copepods.
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Sveen L, Krasnov A, Timmerhaus G, Bogevik AS. Responses to Mineral Supplementation and Salmon Lice ( Lepeophtheirus salmonis) Infestation in Skin Layers of Atlantic Salmon ( Salmo salar L.). Genes (Basel) 2021; 12:genes12040602. [PMID: 33921813 PMCID: PMC8073069 DOI: 10.3390/genes12040602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 04/14/2021] [Accepted: 04/16/2021] [Indexed: 01/29/2023] Open
Abstract
The crustacean ectoparasite salmon louse (Lepeophtheirus salmonis), which severely affects Atlantic salmon health and welfare is one of the main problems of commercial aquaculture. In the present study, fish were fed a diet supplemented with extra minerals through the inclusion of a commercial additive (Biofeed Forte Salmon), substituting wheat in the control diet, before experimental infestation with salmon lice. Lice counts reduced with time but with no apparent effect of the diets. Further, fish fed the mineral diet had an overall higher number of blue (acidic) mucous cells, while the ratio of purple mucous cells was higher in the mineral diet. The transcriptional response in skin was enhanced at 7 dpc (copepodite life stage) in fish fed the mineral diet including immune and stress responses, while at 21 dpc (pre-adult life stage), the difference disappeared, or reversed with stronger induction in the control diet. Overall, 9.3% of the genes affected with lice also responded to the feed, with marked differences in outer (scale + epidermis) and inner (dermis) skin layers. A comparison of transcriptome data with five datasets from previous trials revealed common features and gene markers of responses to lice, stress, and mechanically induced wounds. Results suggested a prevalence of generic responses in wounded skin and lice-infected salmon.
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Dalvin S, Are Hamre L, Skern-Mauritzen R, Vågseth T, Stien L, Oppedal F, Bui S. The effect of temperature on ability of Lepeophtheirus salmonis to infect and persist on Atlantic salmon. JOURNAL OF FISH DISEASES 2020; 43:1519-1529. [PMID: 32882750 DOI: 10.1111/jfd.13253] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 08/05/2020] [Accepted: 08/06/2020] [Indexed: 06/11/2023]
Abstract
The salmon louse (Lepeophtheirus salmonis) is an ecologically and economically important parasite of salmonid fish. Temperature is a strong influencer of biological processes in salmon lice, with development rate increased at higher temperatures. The successful attachment of lice onto a host is also predicted to be influenced by temperature; however, the correlation of temperature with parasite survival is unknown. This study describes the effects of temperature on infection success, and survival on the host during development to the adult stage. To accurately describe infection dynamics with varying temperatures, infection success was recorded on Atlantic salmon (Salmo salar) between 2 and 10°C. Infection success ranged from 20% to 50% and was strongly correlated with temperature, with the highest success at 10°C. Parasite loss was monitored during development at eight temperatures with high loss of lice at 3 and 24°C, whilst no loss was recorded in the temperature range from 6 to 21°C. Sea temperatures thus have large effects on the outcome of salmon louse infections and should be taken into account in the management and risk assessment of this parasite. Improving understanding of the infection dynamics of salmon lice will facilitate epidemiological modelling efforts and efficiency of pest management strategies.
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Affiliation(s)
- Sussie Dalvin
- SLRC - Sea Lice Research Centre, Institute of Marine Research, Bergen, Norway
- Department of Biological Sciences, SLRC - Sea Lice Research Centre, University of Bergen, Bergen, Norway
| | - Lars Are Hamre
- Department of Biological Sciences, SLRC - Sea Lice Research Centre, University of Bergen, Bergen, Norway
| | | | | | - Lars Stien
- Institute of Marine Research, Matredal, Norway
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8
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Landaeta MF, Díaz-Richter C, Muñoz G. Larval parasitic copepods affect early life history traits of a temperate clingfish. Parasitol Res 2020; 119:3977-3985. [PMID: 32833050 DOI: 10.1007/s00436-020-06854-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 08/16/2020] [Indexed: 10/23/2022]
Abstract
Larval copepods are frequent parasites that infest fish larvae along the Chilean coast. Because these parasites develop on fish during the early development, when their bodies are fragile and in a recent stage, they can affect the fishes' early life history traits (ELHT). The goal of this study was to determine the effect of parasitic copepods on the ELHT of the larvae of the clingfish Gobiesox marmoratus (Teleostei: Gobiesocidae) using otolith microstructure analysis. Ichthyoplankton samples were collected during austral winter (July and August 2012), in the inner shelf waters off Valparaiso Bay, central Chile. A total of 95 non-parasitized larvae (NPL) and 95 parasitized (PL) with copepods were randomly selected for subsequent analyses. Parasitized larvae of G. marmoratus were larger than NPL. The right otolith tended to be larger than the left otolith in the fish larvae, but with a higher asymmetry in PL. The PL showed larger otoliths-at-size than the NPL, particularly in smaller larvae (< 8 mm of standard length, SL). Nonetheless, parasitized larvae larger than 8 mm SL showed the opposite trend that is smaller-at-size otoliths than NPL. The Gompertz models indicated that the asymptotic length of NPL doubled the length of PL; this suggests that parasitic copepods affect the maximum size attained by the PL. In conclusion, parasitic copepods negatively affect the ELHT of G. marmoratus larvae and the greater asymmetry can be attributed to parasitism.
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Affiliation(s)
- Mauricio F Landaeta
- Laboratorio de Ictioplancton (LABITI), Facultad de Ciencias del Mar y de Recursos Naturales, Universidad de Valparaíso, Valparaíso, Chile.,Centro de Observación Marino para Estudios de Riesgos del Ambiente Costero (COSTA-R), Universidad de Valparaíso, Avenida Borgoño, 16344, Viña del Mar, Chile
| | - Camilo Díaz-Richter
- Laboratorio de Ictioplancton (LABITI), Facultad de Ciencias del Mar y de Recursos Naturales, Universidad de Valparaíso, Valparaíso, Chile.,Laboratorio de Parasitología Marina, Facultad de Ciencias del Mar y de Recursos Naturales, Universidad de Valparaíso, Valparaíso, Chile
| | - Gabriela Muñoz
- Centro de Observación Marino para Estudios de Riesgos del Ambiente Costero (COSTA-R), Universidad de Valparaíso, Avenida Borgoño, 16344, Viña del Mar, Chile. .,Laboratorio de Parasitología Marina, Facultad de Ciencias del Mar y de Recursos Naturales, Universidad de Valparaíso, Valparaíso, Chile.
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Braden LM, Monaghan SJ, Fast MD. Salmon immunological defence and interplay with the modulatory capabilities of its ectoparasite Lepeophtheirus salmonis. Parasite Immunol 2020; 42:e12731. [PMID: 32403169 DOI: 10.1111/pim.12731] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 03/13/2020] [Accepted: 05/06/2020] [Indexed: 12/16/2022]
Abstract
The salmon louse Lepeophtheirus salmonis (Lsal) is an ectoparasitic copepod that exerts immunomodulatory and physiological effects on its host Atlantic salmon. Over 30 years of research on louse biology, control, host responses and the host-parasite relationship has provided a plethora of information on the intricacies of host resistance and parasite adaptation. Atlantic salmon exhibit temporal and spatial impairment of the immune system and wound healing ability during infection. This immunosuppression may render Atlantic salmon less tolerant to stress and other confounders associated with current management strategies. Contrasting susceptibility of salmonid hosts exists, and early pro-inflammatory Th1 type responses are associated with resistance. Rapid cellular responses to larvae appear to tip the balance of the host-parasite relationship in favour of the host, preventing severe immune-physiological impacts of the more invasive adults. Immunological, transcriptomic, genomic and proteomic evidence suggests pathological impacts occur in susceptible hosts through modulation of host immunity and physiology via pharmacologically active molecules. Co-evolutionary and farming selection pressures may have incurred preference of Atlantic salmon as a host for Lsal reflected in their interactome. Here, we review host-parasite interactions at the primary attachment/feeding site, and the complex life stage-dependent molecular mechanisms employed to subvert host physiology and immune responses.
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Affiliation(s)
- Laura M Braden
- AquaBounty Canada, Bay Fortune, PEI, Canada.,Department of Pathology and Microbiology, Atlantic Veterinary College-UPEI, Charlottetown, PEI, Canada
| | - Sean J Monaghan
- Institute of Aquaculture, University of Stirling, Stirling, UK
| | - Mark D Fast
- Department of Pathology and Microbiology, Atlantic Veterinary College-UPEI, Charlottetown, PEI, Canada
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Heggland EI, Dondrup M, Nilsen F, Eichner C. Host gill attachment causes blood-feeding by the salmon louse (Lepeophtheirus salmonis) chalimus larvae and alters parasite development and transcriptome. Parasit Vectors 2020; 13:225. [PMID: 32375890 PMCID: PMC7201535 DOI: 10.1186/s13071-020-04096-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 04/24/2020] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Blood-feeding is a common strategy among parasitizing arthropods, including the ectoparasitic salmon louse (Lepeophtheirus salmonis), feeding off its salmon host's skin and blood. Blood is rich in nutrients, among these iron and heme. These are essential molecules for the louse, yet their oxidative properties render them toxic to cells if not handled appropriately. Blood-feeding might therefore alter parasite gene expression. METHODS We infected Atlantic salmon with salmon louse copepodids and sampled the lice in two different experiments at day 10 and 18 post-infestation. Parasite development and presence of host blood in their intestines were determined. Lice of similar instar age sampled from body parts with differential access to blood, namely from gills versus lice from skin epidermis, were analysed for gene expression by RNA-sequencing in samples taken at day 10 for both experiments and at day 18 for one of the experiments. RESULTS We found that lice started feeding on blood when becoming mobile preadults if sitting on the fish body; however, they may initiate blood-feeding at the chalimus I stage if attached to gills. Lice attached to gills develop at a slower rate. By differential expression analysis, we found 355 transcripts elevated in lice sampled from gills and 202 transcripts elevated in lice sampled from skin consistent in all samplings. Genes annotated with "peptidase activity" were among the ones elevated in lice sampled from gills, while in the other group genes annotated with "phosphorylation" and "phosphatase" were pervasive. Transcripts elevated in lice sampled from gills were often genes relatively highly expressed in the louse intestine compared with other tissues, while this was not the case for transcripts elevated in lice sampled from skin. In both groups, more than half of the transcripts were from genes more highly expressed after attachment. CONCLUSIONS Gill settlement results in an alteration in gene expression and a premature onset of blood-feeding likely causes the parasite to develop at a slower pace.
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Affiliation(s)
- Erna Irene Heggland
- Department of Biological Sciences and Sea Lice Research Centre (SLRC), University of Bergen, Bergen, Norway
| | - Michael Dondrup
- Department of Informatics and Sea Lice Research Centre (SLRC), University of Bergen, Bergen, Norway
| | - Frank Nilsen
- Department of Biological Sciences and Sea Lice Research Centre (SLRC), University of Bergen, Bergen, Norway
| | - Christiane Eichner
- Department of Biological Sciences and Sea Lice Research Centre (SLRC), University of Bergen, Bergen, Norway.
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11
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Thompson CRS, Fields DM, Bjelland RM, Chan VBS, Durif CMF, Mount A, Runge JA, Shema SD, Skiftesvik AB, Browman HI. The planktonic stages of the salmon louse ( Lepeophtheirus salmonis) are tolerant of end-of-century pCO 2 concentrations. PeerJ 2019; 7:e7810. [PMID: 31632848 PMCID: PMC6796963 DOI: 10.7717/peerj.7810] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 09/01/2019] [Indexed: 01/13/2023] Open
Abstract
The copepod Lepeophtheirus salmonis is an obligate ectoparasite of salmonids. Salmon lice are major pests in salmon aquaculture and due to its economic impact Lepeophtheirus salmonis is one of the most well studied species of marine parasite. However, there is limited understanding of how increased concentration of pCO2 associated with ocean acidification will impact host-parasite relationships. We investigated the effects of increased pCO2 on growth and metabolic rates in the planktonic stages, rearing L. salmonis from eggs to 12 days post hatch copepodids under three treatment levels: Control (416 µatm), Mid (747 µatm), and High (942 µatm). The pCO2 treatment had a significant effect on oxygen consumption rate with the High treatment animals exhibiting the greatest respiration. The treatments did not have a significant effect on the other biological endpoints measured (carbon, nitrogen, lipid volume, and fatty acid content). The results indicate that L. salmonis have mechanisms to compensate for increased concentration of pCO2and that populations will be tolerant of projected future ocean acidification scenarios. The work reported here also describes catabolism during the lecithotrophic development of L. salmonis, information that is not currently available to parameterize models of dispersal and viability of the planktonic free-living stages.
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Affiliation(s)
| | - David M Fields
- Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, United States of America
| | - Reidun M Bjelland
- Austevoll Research Station, Institute of Marine Research, Storebø, Norway
| | - Vera B S Chan
- LEMAR, Institut Français de Recherche pour l'Exploitation de la Mer, UMR 6539 (UBO/CNRS/IRD/Ifremer), Plouzané, France
| | - Caroline M F Durif
- Austevoll Research Station, Institute of Marine Research, Storebø, Norway
| | - Andrew Mount
- Department of Biological Sciences, Clemson University, Clemson, SC, United States of America
| | - Jeffrey A Runge
- School of Marine Sciences, University of Maine, Orono, ME, United States of America.,Gulf of Maine Research Institute, Portland, ME, United States of America
| | - Steven D Shema
- Austevoll Research Station, Institute of Marine Research, Storebø, Norway
| | | | - Howard I Browman
- Austevoll Research Station, Institute of Marine Research, Storebø, Norway
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12
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Michaud DR, Poley JD, Fast MD. Sex-biased gene expression and evolution of candidate reproductive transcripts in adult stages of salmon lice (Lepeophtheirus salmonis). Facets (Ott) 2019. [DOI: 10.1139/facets-2018-0016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The salmon louse Lepeophtheirus salmonis (Krøyer 1837) displays numerous sexually dimorphic characteristics. Insights into their underlying molecular components have only recently been explored, which serve to better understand both the basic biology of the louse, associated impacts on drug sensitivity, and evolution of resistance. Expression of 16 L. salmonis genes putatively involved in sexual dimorphism and reproduction were used to determine differences between sexes and better understand responses to mating using RT-qPCR of pre-adult and adult lice. Analysis of these genes revealed the dynamic nature of sex-biased expression across stages. However, female reception of a spermatophore did not appear to impact the expression of these particular genes. Furthermore six of these transcripts and 84 others identified previously in a large-scale louse transcriptomics experiment were used to estimate differences in evolutionary rates and codon-usage bias of sex-related genes using phylogenetic analysis by maximum likelihood (PAML) and codonW. Results suggest male-biased genes are evolving at significantly greater rates than female-biased and unbiased genes as evidenced by higher rates of non-synonymous substitutions and lower codon-usage bias in these genes. These analyses expand our understanding of interactions of sex-biased expression across the pre-adult and adult life stages and provide foundations for better understanding evolutionary differences in sex-biased genes of L. salmonis.
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Affiliation(s)
- Dylan R. Michaud
- Hoplite Research Group, Department of Pathology and Microbiology, Atlantic Veterinary College, UPEI, Charlottetown, PE C1A 4P3, Canada
| | - Jordan D. Poley
- Hoplite Research Group, Department of Pathology and Microbiology, Atlantic Veterinary College, UPEI, Charlottetown, PE C1A 4P3, Canada
- Center for Aquaculture Technologies Canada, 20 Hope Street, Souris PE C0A 2B0, Canada
| | - Mark D. Fast
- Hoplite Research Group, Department of Pathology and Microbiology, Atlantic Veterinary College, UPEI, Charlottetown, PE C1A 4P3, Canada
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Aldrin M, Jansen P, Stryhn H. A partly stage-structured model for the abundance of salmon lice in salmonid farms. Epidemics 2019; 26:9-22. [DOI: 10.1016/j.epidem.2018.08.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 07/12/2018] [Accepted: 08/16/2018] [Indexed: 11/28/2022] Open
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Harðardóttir HM, Male R, Nilsen F, Eichner C, Dondrup M, Dalvin S. Chitin synthesis and degradation in Lepeophtheirus salmonis: Molecular characterization and gene expression profile during synthesis of a new exoskeleton. Comp Biochem Physiol A Mol Integr Physiol 2019; 227:123-133. [DOI: 10.1016/j.cbpa.2018.10.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 10/09/2018] [Indexed: 02/06/2023]
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15
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Semmouri I, Asselman J, Van Nieuwerburgh F, Deforce D, Janssen CR, De Schamphelaere KAC. The transcriptome of the marine calanoid copepod Temora longicornis under heat stress and recovery. MARINE ENVIRONMENTAL RESEARCH 2019; 143:10-23. [PMID: 30415781 DOI: 10.1016/j.marenvres.2018.10.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 10/10/2018] [Accepted: 10/30/2018] [Indexed: 06/09/2023]
Abstract
Understanding the impacts of global change in zooplankton communities is crucial, as alterations in the zooplankton communities can affect entire marine ecosystems. Despite the economic and ecological importance of the calanoid copepod Temora longicornis in the Belgian part of the North Sea, molecular data is still very limited for this species. Using HiSeq Illumina sequencing, we sequenced the whole transcriptome of T. longicornis, after being exposed to realistic temperatures of 14 and 17 °C. After both an acute (1 day) and a more sustained (5 days) thermal exposure to 17 °C, we investigated gene expression differences with animals exposed to 14 °C, which may be critical for the thermal acclimation and resilience of this copepod species. We also studied the possibility of a short term stress recovery of a heat shock. A total of 179,569 transcripts were yielded, of which 44,985 putative ORF transcripts were identified. These transcripts were subsequently annotated into roughly 22,000 genes based on known sequences using Gene Ontology (GO) and KEGG databases. Temora only showed a mild response to both the temperature and the duration of the exposure. We found that the expression of 27 transcripts varied significantly with an increase in temperature of 3 °C, of which eight transcripts were differentially expressed after acute exposure only. Gene set enrichment analysis revealed that, overall, T. longicornis was more impacted by a sustained thermal exposure, rather than an immediate (acute) exposure, with two times as many enriched GO terms in the sustained treatment. We also identified several general stress responses independent of exposure time, such as modified protein synthesis, energy mobilisation, cuticle and chaperone proteins. Finally, we highlighted candidate genes of a possible recovery from heat exposure, identifying similar terms as those enriched in the heat treatments, i.e. related to for example energy metabolism, cuticle genes and extracellular matrix. The data presented in this study provides the first transcriptome available for T. longicornis which can be used for future genomic studies.
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Affiliation(s)
- Ilias Semmouri
- Ghent University, Laboratory of Environmental Toxicology and Aquatic Ecology, Faculty of Bioscience Engineering, 9000, Ghent, Belgium.
| | - Jana Asselman
- Ghent University, Laboratory of Environmental Toxicology and Aquatic Ecology, Faculty of Bioscience Engineering, 9000, Ghent, Belgium
| | - Filip Van Nieuwerburgh
- Ghent University, Laboratory of Pharmaceutical Biotechnology, Faculty of Pharmaceutical Sciences, 9000, Ghent, Belgium
| | - Dieter Deforce
- Ghent University, Laboratory of Pharmaceutical Biotechnology, Faculty of Pharmaceutical Sciences, 9000, Ghent, Belgium
| | - Colin R Janssen
- Ghent University, Laboratory of Environmental Toxicology and Aquatic Ecology, Faculty of Bioscience Engineering, 9000, Ghent, Belgium
| | - Karel A C De Schamphelaere
- Ghent University, Laboratory of Environmental Toxicology and Aquatic Ecology, Faculty of Bioscience Engineering, 9000, Ghent, Belgium
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Poley JD, Braden LM, Messmer AM, Igboeli OO, Whyte SK, Macdonald A, Rodriguez J, Gameiro M, Rufener L, Bouvier J, Wadowska DW, Koop BF, Hosking BC, Fast MD. High level efficacy of lufenuron against sea lice (Lepeophtheirus salmonis) linked to rapid impact on moulting processes. Int J Parasitol Drugs Drug Resist 2018; 8:174-188. [PMID: 29627513 PMCID: PMC6039351 DOI: 10.1016/j.ijpddr.2018.02.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 02/26/2018] [Accepted: 02/28/2018] [Indexed: 11/29/2022]
Abstract
Drug resistance in the salmon louse Lepeophtheirus salmonis is a global issue for Atlantic salmon aquaculture. Multiple resistance has been described across most available compound classes with the exception of the benzoylureas. To target this gap in effective management of L. salmonis and other species of sea lice (e.g. Caligus spp.), Elanco Animal Health is developing an in-feed treatment containing lufenuron (a benzoylurea) to be administered prior to seawater transfer of salmon smolts and to provide long-term protection of salmon against sea lice infestations. Benzoylureas disrupt chitin synthesis, formation, and deposition during all moulting events. However, the mechanism(s) of action are not yet fully understood and most research completed to date has focused on insects. We exposed the first parasitic stage of L. salmonis to 700 ppb lufenuron for three hours and observed over 90% reduction in survival to the chalimus II life stage on the host, as compared to vehicle controls. This agrees with a follow up in vivo administration study on the host, which showed >95% reduction by the chalimus I stage. Transcriptomic responses of salmon lice exposed to lufenuron included genes related to moulting, epithelial differentiation, solute transport, and general developmental processes. Global metabolite profiles also suggest that membrane stability and fluidity is impacted in treated lice. These molecular signals are likely the underpinnings of an abnormal moulting process and cuticle formation observed ultrastructurally using transmission electron microscopy. Treated nauplii-staged lice exhibited multiple abnormalities in the integument, suggesting that the coordinated assembly of the epi- and procuticle is impaired. In all cases, treatment with lufenuron had rapid impacts on L. salmonis development. We describe multiple experiments to characterize the efficacy of lufenuron on eggs, larvae, and parasitic stages of L. salmonis, and provide the most comprehensive assessment of the physiological responses of a marine arthropod to a benzoylurea chemical.
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Affiliation(s)
- Jordan D Poley
- Hoplite Lab, Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown PE, C1A 4P3, Canada.
| | - Laura M Braden
- Hoplite Lab, Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown PE, C1A 4P3, Canada.
| | - Amber M Messmer
- Centre for Biomedical Research, Department of Biology, University of Victoria, Victoria BC, V8W 3N5, Canada.
| | - Okechukwu O Igboeli
- Hoplite Lab, Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown PE, C1A 4P3, Canada.
| | - Shona K Whyte
- Hoplite Lab, Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown PE, C1A 4P3, Canada.
| | - Alicia Macdonald
- Elanco Canada Limited, 150 Research Lane, Guelph, Ontario N1G 4T2, Canada.
| | - Jose Rodriguez
- Elanco Canada Limited, 150 Research Lane, Guelph, Ontario N1G 4T2, Canada.
| | - Marta Gameiro
- Elanco Canada Limited, 150 Research Lane, Guelph, Ontario N1G 4T2, Canada.
| | - Lucien Rufener
- Elanco Centre de Recherche Santé Animale SA, CH-1566 St.-Aubin, Switzerland; INVENesis LLC, Chemin de Belleroche 14, 2000 Neuchâtel, Switzerland.
| | - Jacques Bouvier
- Elanco Centre de Recherche Santé Animale SA, CH-1566 St.-Aubin, Switzerland; INVENesis LLC, Chemin de Belleroche 14, 2000 Neuchâtel, Switzerland.
| | - Dorota W Wadowska
- Electron Microscopy Laboratory, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, PEI, C1A 4P3, Canada.
| | - Ben F Koop
- Centre for Biomedical Research, Department of Biology, University of Victoria, Victoria BC, V8W 3N5, Canada.
| | - Barry C Hosking
- Elanco Canada Limited, 150 Research Lane, Guelph, Ontario N1G 4T2, Canada.
| | - Mark D Fast
- Hoplite Lab, Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown PE, C1A 4P3, Canada.
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Eichner C, Dondrup M, Nilsen F. RNA sequencing reveals distinct gene expression patterns during the development of parasitic larval stages of the salmon louse (Lepeophtheirus salmonis). JOURNAL OF FISH DISEASES 2018; 41:1005-1029. [PMID: 29368347 DOI: 10.1111/jfd.12770] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 11/08/2017] [Accepted: 11/10/2017] [Indexed: 06/07/2023]
Abstract
The salmon louse (Lepeophtheirus salmonis), an ectoparasitic copepod on salmonids, has become a major threat for the aquaculture industry. In search for new drugs and vaccines, transcriptome analysis is increasingly used to find differently regulated genes and pathways in response to treatment. However, the underlying gene expression changes going along with developmental processes could confound such analyses. The life cycle of L. salmonis consists of eight stages divided by moults. The developmental rate of salmon lice on the host is not uniform. Individual- and sex-related differences are found leading to individuals of unlike developmental status at same sampling time point after infection. In this study, we analyse L. salmonis from a time series by RNA sequencing applying a method of separating individuals of different instar age independent of sampling time point. Lice of four stages divided into up to four age groups within the stage were analysed in triplicate (total of 66 samples). Gene expression analysis shows that the method for sorting individuals was successful. Many genes show cyclic expression patterns over the moulting cycles. Overall gene expression differs more between lice of different age within the same stage than between lice of different stage but same instar age.
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Affiliation(s)
- C Eichner
- Sea Lice Research Centre, Department of Molecular Biology, University of Bergen, Bergen, Norway
| | - M Dondrup
- Sea Lice Research Centre, Department of Informatics, University of Bergen, Bergen, Norway
| | - F Nilsen
- Sea Lice Research Centre, Department of Biology, University of Bergen, Bergen, Norway
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Borchel A, Nilsen F. A novel gene-family involved in spermatophore generation in the economically important salmon louse Lepeophtheirus salmonis. Mol Reprod Dev 2018; 85:478-489. [PMID: 29633415 DOI: 10.1002/mrd.22984] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Revised: 04/03/2018] [Accepted: 04/04/2018] [Indexed: 11/06/2022]
Abstract
The salmon louse (Lepeophtheirus salmonis) is an important parasite of Atlantic salmon (Salmo salar). It is widely spread in aquaculture facilities and leads to economic losses every year. As it has developed resistances against many common treatments, new control methods must be established. Here we characterize a novel gene family of the salmon louse, consisting of two genes, which has not been described in other species before. We analyzed temporal expression patterns of both genes, the localization of mRNA and protein. An RNAi mediated gene knockdown lead to information about the function of the protein. Overall, these two genes are expressed only in sperm ducts of male sea lice. The mucin-like proteins can additionally be found in the wall of spermatophores, which are responsible for sperm transfer to females. Knockdown showed that both genes are essential for successful fertilization of females. Overall, all results indicate that the two analyzed genes are necessary for reproduction in sea lice as they are essential for the formation of a wall surrounding the spermatophores, which is needed for fertilization. Therefore, we name them Mucin-like spermatophore wall protein 1 & 2 (MLSWP1 & MLSWP2). Analysis of sequence data from other copepod species suggests that MLSWPs are present in many copepod species and may also play a similar role in reproduction in those species.
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Affiliation(s)
- Andreas Borchel
- SLRC-SeaLiceResearch Centre, Department of Biology, University of Bergen, Bergen, Norway
| | - Frank Nilsen
- SLRC-SeaLiceResearch Centre, Department of Biology, University of Bergen, Bergen, Norway
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Aldrin M, Huseby R, Stien A, Grøntvedt R, Viljugrein H, Jansen P. A stage-structured Bayesian hierarchical model for salmon lice populations at individual salmon farms – Estimated from multiple farm data sets. Ecol Modell 2017. [DOI: 10.1016/j.ecolmodel.2017.05.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Mrak P, Bogataj U, Štrus J, Žnidaršič N. Cuticle morphogenesis in crustacean embryonic and postembryonic stages. ARTHROPOD STRUCTURE & DEVELOPMENT 2017; 46:77-95. [PMID: 27816526 DOI: 10.1016/j.asd.2016.11.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 10/19/2016] [Accepted: 11/01/2016] [Indexed: 06/06/2023]
Abstract
The crustacean cuticle is a chitin-based extracellular matrix, produced in general by epidermal cells and ectodermally derived epithelial cells of the digestive tract. Cuticle morphogenesis is an integrative part of embryonic and postembryonic development and it was studied in several groups of crustaceans, but mainly with a focus on one selected aspect of morphogenesis. Early studies were focused mainly on in vivo or histological observations of embryonic or larval molt cycles and more recently, some ultrastructural studies of the cuticle differentiation during development were performed. The aim of this paper is to review data on exoskeletal and gut cuticle formation during embryonic and postembryonic development in crustaceans, obtained in different developmental stages of different species and to bring together and discuss different aspects of cuticle morphogenesis, namely data on the morphology, ultrastructure, composition, connections to muscles and molt cycles in relation to cuticle differentiation. Based on the comparative evaluation of microscopic analyses of cuticle in crustacean embryonic and postembryonic stages, common principles of cuticle morphogenesis during development are discussed. Additional studies are suggested to further clarify this topic and to connect the new knowledge to related fields.
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Affiliation(s)
- Polona Mrak
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, SI-1000 Ljubljana, Slovenia.
| | - Urban Bogataj
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, SI-1000 Ljubljana, Slovenia
| | - Jasna Štrus
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, SI-1000 Ljubljana, Slovenia
| | - Nada Žnidaršič
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, SI-1000 Ljubljana, Slovenia
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Poley JD, Sutherland BJG, Jones SRM, Koop BF, Fast MD. Sex-biased gene expression and sequence conservation in Atlantic and Pacific salmon lice (Lepeophtheirus salmonis). BMC Genomics 2016; 17:483. [PMID: 27377915 PMCID: PMC4932673 DOI: 10.1186/s12864-016-2835-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 06/13/2016] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Salmon lice, Lepeophtheirus salmonis (Copepoda: Caligidae), are highly important ectoparasites of farmed and wild salmonids, and cause multi-million dollar losses to the salmon aquaculture industry annually. Salmon lice display extensive sexual dimorphism in ontogeny, morphology, physiology, behavior, and more. Therefore, the identification of transcripts with differential expression between males and females (sex-biased transcripts) may help elucidate the relationship between sexual selection and sexually dimorphic characteristics. RESULTS Sex-biased transcripts were identified from transcriptome analyses of three L. salmonis populations, including both Atlantic and Pacific subspecies. A total of 35-43 % of all quality-filtered transcripts were sex-biased in L. salmonis, with male-biased transcripts exhibiting higher fold change than female-biased transcripts. For Gene Ontology and functional analyses, a consensus-based approach was used to identify concordantly differentially expressed sex-biased transcripts across the three populations. A total of 127 male-specific transcripts (i.e. those without detectable expression in any female) were identified, and were enriched with reproductive functions (e.g. seminal fluid and male accessory gland proteins). Other sex-biased transcripts involved in morphogenesis, feeding, energy generation, and sensory and immune system development and function were also identified. Interestingly, as observed in model systems, male-biased L. salmonis transcripts were more frequently without annotation compared to female-biased or unbiased transcripts, suggesting higher rates of sequence divergence in male-biased transcripts. CONCLUSIONS Transcriptome differences between male and female L. salmonis described here provide key insights into the molecular mechanisms controlling sexual dimorphism in L. salmonis. This analysis offers targets for parasite control and provides a foundation for further analyses exploring critical topics such as the interaction between sex and drug resistance, sex-specific factors in host-parasite relationships, and reproductive roles within L. salmonis.
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Affiliation(s)
- Jordan D Poley
- Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, PE, C1A 4P3, Canada
| | - Ben J G Sutherland
- Department of Biology, Centre for Biomedical Research, University of Victoria, 3800 Finnerty Rd, Victoria, BC, V8W 3 N5, Canada.,Present address: Département de biologie, Institut de Biologie Intégrative et des Systèms (IBIS), Université Laval, 1030 Avenue de la Medecine, Québec, QC, Canada
| | - Simon R M Jones
- Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, BC, V9T 6 N7, Canada
| | - Ben F Koop
- Department of Biology, Centre for Biomedical Research, University of Victoria, 3800 Finnerty Rd, Victoria, BC, V8W 3 N5, Canada
| | - Mark D Fast
- Department of Pathology & Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, PE, C1A 4P3, Canada.
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McEwan GF, Groner ML, Fast MD, Gettinby G, Revie CW. Using Agent-Based Modelling to Predict the Role of Wild Refugia in the Evolution of Resistance of Sea Lice to Chemotherapeutants. PLoS One 2015; 10:e0139128. [PMID: 26485023 PMCID: PMC4618729 DOI: 10.1371/journal.pone.0139128] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 09/08/2015] [Indexed: 11/18/2022] Open
Abstract
A major challenge for Atlantic salmon farming in the northern hemisphere is infestation by the sea louse parasite Lepeophtheirus salmonis. The most frequent method of controlling these sea louse infestations is through the use of chemical treatments. However, most major salmon farming areas have observed resistance to common chemotherapeutants. In terrestrial environments, many strategies employed to manage the evolution of resistance involve the use of refugia, where a portion of the population is left untreated to maintain susceptibility. While refugia have not been deliberately used in Atlantic salmon farming, wild salmon populations that migrate close to salmon farms may act as natural refugia. In this paper we describe an agent-based model that explores the influence of different sizes of wild salmon populations on resistance evolution in sea lice on a salmon farm. Using the model, we demonstrate that wild salmon populations can act as refugia that limit the evolution of resistance in the sea louse populations. Additionally, we demonstrate that an increase in the size of the population of wild salmon results in an increased effect in slowing the evolution of resistance. We explore the effect of a population fitness cost associated with resistance, finding that in some cases it substantially reduces the speed of evolution to chemical treatments.
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Affiliation(s)
- Gregor F. McEwan
- Centre for Veterinary and Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, PE, Canada, C1A 4P3
- * E-mail:
| | - Maya L. Groner
- Centre for Veterinary and Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, PE, Canada, C1A 4P3
| | - Mark D. Fast
- Department of Anatomy and Physiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, PE, Canada, C1A 4P3
| | - George Gettinby
- Department of Mathematics & Statistics, University of Strathclyde, Richmond Street, Glasgow, G1 1XH, Scotland, UK
| | - Crawford W. Revie
- Centre for Veterinary and Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, PE, Canada, C1A 4P3
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